Dietary RISCO NUTRIFOUR multistrain multikingdom probiotic consortia improves meat quality carcass traits and growth efficiency in heat stressed broilers

Heat stress (HS) compromises broiler productivity by depressing growth, meat quality, and physiological resilience. This trial evaluated the effects of a novel multi-strain probiotic solution, RISCO NUTRIFOUR (MSPS), in 288 Ross 308 broilers reared under standard environmental temperatures until day 28, followed by exposure to cyclic HS (35 ± 1°C, 09:00–17:00; 23 ± 1°C thereafter) until day 42. Birds were randomly allotted to six dietary treatments within the basal diet: MSPS at 1, 2, or 4 mL kg-¹; Bacillus subtilis (1 mL kg-¹); S. cerevisiae (1 mL kg-¹); or an unsupplemented control (n = 8 pens * 6 birds). At day 42, breast meat quality and carcass characteristics of heat-stressed broilers were assessed. Also, the performance index (PI), European production efficiency factor (EPEF), and feed efficiency (FE) of the production cycle were calculated. MSPS at 1 mL kg-¹ significantly (p < 0.05) enhanced PI (+ 18.5%), EPEF (+ 18.2%), and FE (+ 13.6%) versus the negative control. Also, cooking loss percentage fell by 40.5% and breast meat lightness (L*) and whiteness index increased (p < 0.05). MSPS improved ultimate pH and reduced core temperature 24 h post-mortem, indicating better metabolic recovery. No adverse effects on relative internal organ weights, texture, or sensory traits were noted (p > 0.05). GC-MS revealed that MSPS has antioxidant and antimicrobial metabolites that may underpin these responses. In conclusion, MSPS, particularly at 1 mL kg-¹, mitigates HS-induced detriments to meat quality and growth, resulting in improved PI, EPEF, and FE, offering a practical antibiotic-free strategy for the broiler industry in hot climates.